A ballet student with her arms and a leg extended spins with an initial rotational speed of 0.90rev/s. As she draws her arms and leg in toward her body, her rotational inertia becomes 0.80 kg⋅m2 and her rotational velocity is 4.1rev/s.

Determine her initial rotational inertia.

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Physics

Today, 15:43

A ballet student with her arms and a leg extended spins with an initial rotational speed of 0.90rev/s. As she draws her arms and leg in toward her body, her rotational inertia becomes 0.80 kg⋅m2 and her rotational velocity is 4.1rev/s.

Determine her initial rotational inertia.

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Kennedy Poole · Answer 1

Initial inertia = 3.6 kg. m^2

final inertia = 0.80 kg. m^2rotational velocity final = 4.1 rev/s

rotational velocity initial = 0.90 rev/s

lo = lf (final inertia) * Wf (rotational velocity final) / Wo (rotational velocity initial)

lo = 0.8*4.1 / 0.90 = 3.6 kg m2

A ballet student with her arms and a leg extended spins with an initial rotational speed of 0.90rev/s. As she draws her arms and leg in toward her body, her rotational inertia becomes 0.80 kg⋅m2 and her rotational velocity is 4.1rev/s.Determine her initial rotational inertia.

A ballet student with her arms and a leg extended spins with an initial rotational speed of 0.90rev/s. As she draws her arms and leg in toward her body, her rotational inertia becomes 0.80 kg⋅m2 and her rotational velocity is 4.1rev/s.

Determine her initial rotational inertia.